Assessing of Kappa-Casein Polymorphism in Ukrainian Charolais Cattle and Its Associations With Productivity Traits

Abstract

Much attention is paid to the study of kappa-casein gene polymorphism in dairy breeds of cattle. Moreover, there is a lack of research on kappa-casein polymorphism in cattle beef breeds. Knowing that different alleles of the kappa-casein gene have different effects on milk yield and milk protein content, it would be important to study the exact allele associations in Ukrainian Charolais cattle. In addition, it would be relevant to find out whether there is an effect of different alleles of the kappa-casein gene on growth parameters in offspring. In addition, the current study would be highly relevant due to no previous research of κ- Cn in Ukrainian Charolais cattle. The polymorphism of the kappa-casein (κ-Cn) gene was studied in the population of Ukrainian Charolais cattle (n=29), "Privilla" agricultural company (Ukraine, Luhansk region) using the PCR-PDRF method. DNA was extracted from blood using the DNA Sorb isolation kit (AmplySens). Hind III restriction enzyme (FastDigest, Thermo Scientific) was used to see 2 allelic variants of κ-Cn polymorphism, which are A (273 bp) and B (182, 91 bp). The frequency of the A allele was 0.57±0.065 and 0.43±0.065 of the B allele. According to the genotyping results, allele frequency distribution in the population of 2021 did not reliably differ from the population of 2012. As a result, allele frequencies of the kappa-casein gene in 2012 for allele A was 0.61±0.054 and for B 0.39±0.054. This indicates the lack of selection pressure on population dynamics such as selective selection and gene drift over a period of 10 years. The frequency of AA genotypes was equal to 0.31, of BB genotype to 0.17 and of AB to 0.52. It was found that the theoretically expected number of genotypes, calculated according to the Hardy-Weinberg principle, did not reliably differ from the actual number. It could be related to current alleles being within an equilibrium state. In cattle with different genotypes of the κ-Cn gene, the values of the liveweight gain (kg) and the average daily gain (g) were calculated. In cattle with the BB genotype, there was an increase in the weight gain of their calves at weaning at 210 days (206.0±5.65 kg). In addition, the average daily gain of calves was 981.0±26.94 g, compared to genotypes AA (201.4±8.08 kg and 958.9±37.85 g, respectively) and AB – (196.8±2.45 kg and 936.9±11.73 g, respectively). Though, there were no significant differences between AA, BB and AB genotypes considering the studied parameters. Keywords: gene, kappa-casein, cattle, Charolais, polymorphism, meat productivity.